Utilization of the 10B (n, alpha)7 Li reaction for Neutron Capture Therapy (NCT) provides potentially optimal conditions for radiotherapy. Physiological localization of boron in tumor permits selective irradiation of cancer cells within the radiation field, as the range of the He and Li ions is approximately 10 micron in tissue. The insensitivity of the 10B (n, alpha)7 Li reaction to oxygen concentration and the high RBE in a very localized region results in a low radiation effect on non-target tissues from the incident neutron beam. Borated compounds recently described in the literature are reported to be selectively bound to neoplasms. For example chlorpromazine, known to combine with pigment in melanoma, has been synthesized with approximately 25% by weight boron. The resulting high tumor-to-blood ratios obviate one of the two main problems in initial clincial trials. It is proposed to synthesize these compounds and evaluate toxicity and tissue distribution using established techniques. An epithermal neutron beam which has already been developed and whose physical and biological parameters are well-known will be used to test the efficacy of the new compounds for NCT in animals. The use of a epithermal reactor beam allows deeper penetration and provides tumor/normal tissue dose ratios significantly in excess of thermal neutron therapy beams, thereby removing the 2nd significant problem of poor depth dose distribution encountered previously.